Processing of Acousto-Ultrasonic Data for analysis of temperature parameters and damage detection in CFRP Structures

Author:

Moix-Bonet, Maria

Other authors:

Boller, Christian

Abstract:

The aim of this work is to study the damage detection capability by means of Lamb wave propagation
in a CFRP omega-stringer stiffened panel in presence of changing environmental conditions.
Temperature influence in Lamb wave propagation as well as damage detection methods for changing
environmental conditions have already been studied on other stiffened structures, although for
different materials and geometries.
For the actuation and sensing a network of bonded piezoceramic transducer has been used and the
temperature test has been performed introducing the structure in an oven with temperatures going
from 40°C until 80°C. A total of 13 delaminations or debondings have been induced in three zones of
the structure geometry with a mobile impactor. After the impact introduction the temperature test
has been repeated in order to compare the data acquired before and after the impact in the same
environmental conditions.
The temperature test has been used to first identify by experimental means the variations in Lamb
wave propagation through the given CFRP-stiffened panel caused by temperature. Afterwards, signal
processing permits to determinate the adequate modes, frequencies and parameters in order to
detect damage. Dispersion curves assisted by a scatter study prove that A0 mode is the most suited
mode for SHM means since it is the most sensitive to alterations in the structure. The last part of the
study is finds several parameters capable to detect damage in spite of temperature variations.